diff --git a/startup.bash b/startup.bash
index a90fb3d..cfd9717 100644
--- a/startup.bash
+++ b/startup.bash
@@ -1,13 +1,35 @@
-#!/usr/bin/env bash -x
+#!/usr/bin/env bash
 
+joinztnet() {
+	local ztaddrlist ztoutput ztaddr
+	ztaddrlist="$1"
+
+	# Yes, this is UUOC. No, I won't be changing it.
+	# shellcheck disable=2002,2162
+	cat "$ztaddrlist" | while read ztaddr; do
+		# `zerotier-cli join $address` will return the same success message if already joined
+		#  to $address
+		ztoutput=$(zerotier-cli join "$ztaddr")
+		if [[ "$ztoutput" != "200 join OK" ]]; then
+			printf "Error: Unable to join ZeroTier network with ID: %s\nOutput: %s" \
+				"$ztaddr" \
+				"$ztoutput"
+			exit 1
+		fi
+	done
+}
 
 ####
 # Runtime Config
 
 # Copy authorized_keys secret to the user's ssh config folder
 #  (symlinking will not do, because sshd checks perms of the file tree above the target of the link)
-install -Dm 600 -o thurstylark -g thurstylark /run/secrets/tl-weechat-authorizedkeys /home/thurstylark/.ssh/authorized_keys
-
+install \
+	-Dm 600 \
+	-o thurstylark \
+	-g thurstylark \
+	/run/secrets/tl-weechat-authorizedkeys \
+	/home/thurstylark/.ssh/authorized_keys
 
 
 ####
@@ -16,6 +38,9 @@ install -Dm 600 -o thurstylark -g thurstylark /run/secrets/tl-weechat-authorized
 # Start zerotier-one in daemon mode
 zerotier-one -d
 
+# Attempt to join the specified ZeroTier networks
+joinztnets /run/secrets/tl-weechat-ztnetaddrs
+
 # Start sshd
 sshd